The present invention relates to a vibration motor installed, for example, in the housing of a computer game controller, and more particularly to a vibration motor in which impact sounds produced as a result of axial movement of a rotary shaft are reduced.
For example, as shown in FIG. 3, a DC motor 111 for generating vibration described in Japanese Patent Laid-Open Publication No. H11-356008 is disposed on a mounting seat 110 in the housing of a computer game controller. The DC motor 111 comprises a magnet 114, which is provided on the inner face of a casing 112, an armature 115, which is pivotally mounted on a motor shaft 113, a commutator 117, which is fixed to the motor shaft 113 and connected to a DC power supply by brushes 116, a terminal unit 118 and the like, and is configured so that the armature 115 is rotated by electromagnets due to the interaction of the magnet 114 and the current, in response to the DC power supply.
At the upper end part of the casing 112, the motor shaft 113 is supported by metal 119, and at the lower end part of the casing 112, the motor shaft 113 is supported by metal 119A. Furthermore, when assembling the armature 115, predetermined gap G is provided in advance between the axial center line Y of the armature 115 and the axial center line X of the magnet 114, this being formed so as to enhance the attraction of the magnet 114 with respect to the armature 115.
Furthermore, in order to impart a predetermined vibration to the DC motor 111, a weight 120 is eccentrically mounted on the motor shaft 113 that protrudes outside the casing 112.
Furthermore, the rotation of the DC motor 111 causes the motor shaft 113 to move up and down in conjunction with eccentric oscillation of the weight 120. At this time, a stopper 121 that is fixed to the motor shaft 113 impacts the casing 112, and impact sounds are generated.
Here, in order to enhance the attraction of the magnet 114, a permanent magnet 122 having a predetermined attractive force is mounted in the weight 120.
However, in the motor for generating vibration in Japanese Patent Laid-Open Publication No. H11-356008, there is a problem in that, if the stopper 121 is made of a hard material, the impact sounds will be greater than in the case where the stopper 121 is made of a soft material, such that the impact sounds cannot be sufficiently reduced.
Meanwhile, if the stopper 121 is made of a soft material, while the impact sounds generated by the axial movement of the motor shaft 113 will be reduced, it is possible that the stopper 121 will be deformed and thus will impact the metal 119A. Here, there is a problem in that the cylindrical metal 119A is fixed simply by way of insertion into the cylindrical bearing holder 112A, and therefore, if the stopper 121 deforms and impacts the metal 119A, it is possible that the metal 119A will be moved out of the casing 112 such that the reliability of the motor will tend to be inferior.